Die



May 30, 1944. Q J, WELCOME 2,349,920

DIE

Original Filed Aug. 19', 1940 C'r! J. Welcome.

Patented May 30, 1944 i @.g;

N UNITED STATES rATENT OFFICE DIE 'Carl'.ll Welcome, Toledo, Ohiooriginal application August 19, 1940, serial No. 353,195. Divided andthis application August 25,1941, serial No. 408,182 f 3 claims., (ci.iii- 47) My invention relates `tothe-art of duplicating Aobjects vandparticularly to the fabrication of molds, tools and `dies for accuratelyreproducing objects irrespective lof intricacy of design or form, and isa division of my copending application, Serial No. 353,l95,filed August19, 1940.

The invention comprehends simple, inexpensive dies, tools and molds forduplicating objects to exact form and dimensions, eliminating tedius andtime consuming operations which require a, 10

high degree of skill.

The invention includes the provision of a die or cavity molcl formed ofan exceedingly hard metal which Will withstand heat, abrasion andcorrosion and which can be readilyand inexpensivelyy 1# -reconditionedwithout the necessity of complicated machine operations.

It is an object of my invention to provide improvements in themanufacture of mold's,tools and dies which makes very easy and rapidpro-1 20 or dies having a low coeflicient of expansion 'ari'daq whichare more rsistant to heat,"abra`sio`nand most chemical reactions, thanarev dies now made of 'tool steel or alloy steel.

' It is an object of my invention tofacdomplish nien which Will be anaccurate replica ofv the model by electrodepositing metallic layers onthe surface of the model. It is an object of my invention to produce adie formed of superimposed'metals vs /herein the `face metal exposed tovvvearis bonded to an underlying or foundation r'netal,l the latter"being capable `of withstandingwithout deterioration the removal of thefacefmetal. f 4 l It is an object of my invention ,toproducea ,die bydepositing on a `f undatio'n layer or metallic structure, having theshape of the Working surface of the die, a hard metal to` form albacking which also takes `the shape of the workingfno.

surface of the die. y Y,

l It is an objectof my invention to make molds, tools, and dies byworkmenpf Yo itliiiar'y skill Iin `a shorter time than has heretoforebeen retion of hobbing out, and hand tooling which is necessary at thepresent time.

It is an object of my invention to make molds and dies of metalliclayers which are deposited electrically or otherwise upon the surface ofthe object to be duplicated including: a hard metal capable of Abeingstripped and reconditioned vforming the face or working surface; asofter metal preferably of the base metal type capable of withstandingthe removal or stripping operation of the face metal Withoutdeterioration constituting the foundation metal or metallic shell havingthe shape of the working surface; a primary base substantially of thesame metal as that face, having toughness, hardness, heat resistance andshock resistance; and a secondary base of malleable or softer metalwhich can be applied mechanically and shaped to conform to vthe press ormachine used for operating the die.

Further objects and advantages are within the scope of this inventionsuch as relate to the arrangement, operation and function of the relatedelements of the structure, to various details of yconstruction and tocombination-s of` parts, elements per se, and to economies ofmanufacture and numerous other features as will be apparent `from aconsideration of the specification and drawing ,of a form of theinvention, which may vlie-preferred, in which:

Figurer 1 isa side elevational view with a portion in section of apattern or article to be duplicatedin accordance with the method of myinvention; 1

Figure 2 is a sectional view illustrating the die thmakmg of tools anddies by hsk-medwokwg; Ablock produced in accordance with my improvedFigure 2;

Figure 4 is a cross sectional view of the article to be duplicated,illustrating that a portion of the surface to be duplicated is coatedwith a current yconductive substance.

, Figure 5 represents the step of my improved methodin establishing thesurface to be duplicated as a cathode in an electro-plating bath;

Figure 6 is a cross-section of the article illustrating the built upfoundation shell produced by an electro-plating bath;

l Figure 7 represents the step of my improved method in establishing thedeposited shell as a cathode in an ,electro-plating bath for depositinga reinforcing backing or primary base therequired, elminatingthslowandlaborious opera- .-55 Y .Figure `8 illustrates the backed electro-platedThe principles of the invention are illustrated in their practicalapplication to the fabrication of a composite die block used forduplicating an article by utilizing a synthetic plastic material.However, the invention is not limited to this particular application butthe-same comprehends the tact with the article is established as acathode in an electro-plating chromium bath so that a film of apredetermined thickness is deposited on the copper shell to constitutethe face or wearing surface of the die. This chromium lm should be ofsubstantially the same over-all thickness of the coatin-gs employed totreat the article and establishing the selected surface as a cathode inthe copper electro-plating bath. The resulting composite metallicstructure is bonded or Y fixed to a suitable metallic support orsecondary base applied to the primary base or chromium backing. I havefound that the application of employment of the principles hereinafterenu-l g merated for producing tools for reproducing surface contours orarticles utilizing metals or other upon a foundation metallic shell orupon a pri mary reinforcing metallic base. The foundation shell isformed or made of a metal somewhat more ductile having a different colorcharacteristie than that of the face metal and capable of withstandingwithout impairment the removal of the face metal. The foundation-shellis preferably produced by the deposition of a suitable metal upon thesurface'to be duplicated to take the shape of the same. This foundationshell is bonded to or reinforced by a metallic primary base suitablyapplied thereto;r the surface of the primary base taking also the shapeor contour of the surface to be duplicated.' The primary base is carriedby a suitable support made of a malleable metal, I

I have found out after considerable research and experimentation that adie or mold can be produced in a highly efficient and inexpensive mannerby employing the followingsteps. The article or contourto be duplicatedis preferably made or rendered capable of receiving without impairment ametallic deposition, the same is then established as a cathode in anelectro-plating bathso that a metallic shell of the foundation metal isbuilt up having the corresponding configuration. I have yfound that basetype metals that canrbe electrically deposited without great cost suchas copper, nickel or cobalt serve the purpose very effectively asfoundation metals for building up the metallic shell as any one of thesemetals has the characteristics desired with referl 'ence to ductility,degree of hardness and capability of withstanding without impairmentcer- Vtain physical or chemical actions to which the kthe secondary basecan be effectively carried out before separating the article from thecopper shell and that the deposition of the die face or `chromium lm canbe very effectively accom plished after the `secondary base has beenapplied. In addition it is contemplated within the spirit of theinvention to remove or dissolve the foundation metal by suitable agentssuch as by the application of nitric acid and apply to the primary baseor chromium backing the hard face metaL building up the same to thethickness not only of coatings employed to treat the article andestablish the selected surface as a cathode, -but also to the thicknessof the layer of the foundation metal, so that the forming tool or diewill comprise the hard face metal or workingsurface and the reinforcingbases or hackings.

Referring to the drawing which illustrates a practicalappHcation of theinvention for producing as a forming tool a die element in which likereference characters are employed to designate like parts; in Figure 1is shown a pattern or an article to be duplicated which is in the formof a paper weight I0 constructed to the actual contour and dimensionsdesired to be present inthe replicas or facsimiles produced by using4the composite cavity die formed by the separable elements I2 and i4, across-section of which is illustrated in Figures 2, 3 and 10.

In carrying out my invention for duplicating articles, the surface orcontour to be duplicated, whichv may be of metal, wood, plasticmaterial. wax or other suitable material, is first cleaned withasuitable cleaner or solvent. If the surface of the article is of amaterial unsuitable to receive a metallic coating, its surface istreated to receive a metallic coating without impairment or ispreferably rendered impervious to an electro-plating bath by applyingany suitable acid repellent substance as, for example, beeswax which isdistributed so as to produce a uniform lm or coating thereon. Theparticular portion of the surface of the treated article selected toconstitute or form one of the elements of the die block, such as thelower element I4, is arranged to receive a metallic shell such as bycovering the Asame with current conductive coating for receiving byelectro-plating a metallic deposition thereon. I have found that aconductive coating produced by applying a solution containing graphitein suspension or any other suitable conductor, such as plumbago oraluminum paint is Vvery effective. In the embodiment illustratedparticularly'shown in Figure 4, the base surface |'6 of the paper weightl0 which will constitute the lower die section i4 is coated as at i1with a solution containing graphite so as to give a film of uniformthickness. The uniformity and the thicknessof the conductive coating Ilare carefully controlled in order to secure a high degree of accuracy inthe duplication of the ex- 'act dimensions .and 'contour of the base I6of the article I0.'

The article I witnfits conductive coating I1 is then placed or immersedin an electro-plating bath Ill and established asa cathode so that alayer of copper, nickel, cobalt or other suitable 'material is depositedon Athe outer surface of the I and a spec-inc gravity density to producea fine grained, ductile, smooth plate 'or initial electrical depositionand capable of being modified lor controlled so that during the buildingup of the shell, uneven ror irregular portions may bel formed at theback or rear of thelinitial deposition or surface layer, as particularly`'shown in Figures 5 and '6. I have found that a shell or plateproducedby van `electro-deposition of a base type metal such as copper servesthe purpose very effectively, not only due to their low cost but becausethey perform the function of readily indicating the wearing of the dieduring use and also allow the reconditioning of the die, permittingchanges when desired without tedious and time consuming operations whichrender metals of this type very adaptable forV the formation of a orfoundation shell 20 is bonded to a metallic or 0 primary base bypreferably immersing the treated article with its foundation metal 2l)in a chromium depositing bath, as shown in Figure '7, land the exposedsurfaceor rear face of the metallic shell 20 is established as a cathodefor the electrodeposition thereon ol"l chromium layer 22. The layer ofchrome is builtup to the desired thickness by allowing the article withits metallic shell 2li to remain in the bath for a predetermined periodof time, rapidity of the deposition may be regulated and accomplished bychanging the temperature concentration of the bath and current density.`

The pattern il) `with its deposited electroplated coatings 2t and 22 isthen removed from the chromium hath I9 and rinsed preferably in hot andcold Water or' other suitableage'nt to remove objectionable orl loosematter'.

The article Il) is then preferably separated from the metallicstructurev 23 formed by the metallic coatings 20 and 22 by any suitablemeans. I have found that by subjecting the article III or metallicstructure 23 to heat, due to the difference of expansion between thebonded metal coatings 2Q and 22 and the article Hl. -a very rapid andef.. fective separation can be secured. This separation produces acomposite metallic structure formed by the electro-plated coatings 20and 22 having a front surface corresponding in contour to that of thebase'IE of article Il] as is particularly shown in Figure 8.

The surface or face 25 of the metallic shell 2li, which has been incontact with the base I5 of the pattern or article to be duplicated, iscleaned with a suitable solvent or degreasing agent to remove anypossible traces of the current conductive substance or graphite coatingI1 formerly applied to the surface of the article. The metallicstructure 23 is thereafter placed in a chromic acid bath 2l preferablyhaving the particular constituents and incorporating the features setforth in United States Patent No. 1,881,885 of October ll, 1932, and the`front face 25 is established as a cathode for the deposition of achrome film of fine quality deposited at a high current density andtemperature. The metallic structure is allowed to rem-ain in the bathuntil a layer `2li of the very fine metallic chromium of predeterminedthickness is deposited on surface 25. the layerv 28` having a thicknessequal to the thickness` of the material covering the surface of thearticle to be duplicated such as that produced by the coating applied intreating the article and that of the conductive coating, so that the diewill have the exact form and accurate dimensions of the model. Thecomposite metallic structure formed by the chromium depositions 22 and23 covering the soft metallic shell 2U of such metals as copper, nicke1or cobalt is removed from the chromium bath and preferably polished tothe desired gloss and smoothness after cleaning the same or removing anyforeign matter therefrom. The rear surface 30 of the chromium layer 22is bonded or secured to a suitable support or secondary backing 32 whichmay have the shape and configuration illustrated in Figure` 10 so as tobe used as the lower element I 4 of the die block. The secondary backingis preferably made of a metalsecured by electro-deposition to the rearface 30 of thechromium plate 22, the metal being preferably of malleablecharacter 4soit'hat machine operations can be performed with` ease andspeed in order to give the shape and dimensions necessary to conformthemachine or press used for` producing the facsimiles or replicas. Icontemplate the employment of the Goldschmidt process described inUnited States Patent No.

`578,868 or by aluminothermic welding method for 5 bonding the secondarybacking tothe surfaceS of the multi-layer metallic structure. However,this secondary backing can be produced by setting or solidifying moltenmetal around the metallic structure or by increasing the thickness ofthe metallic chro'mic deposition 22 to the desired size.

In the practical application of the invention for producing the lowerdie element I4, the steps and operations have been described as beingperformed in a `certain predetermined order. However effective resultscan be secured by changing their sequence. I have found that in theproduction of stamping dies or molds having complicated contours orintricate designs, it is very advantageous to apply the secondarybacking or base 32 while the composite metallic structure 23 is incontacting engagement with the base I6 of the article Ill and that thestep in separating the metallic structure from the article can becarried out after the secondary backing has been bonded or appliedthereto. This procedure climi'nates any possible distortion of themetallic structure 23 when the secondary base is applied by casting oradding a molten metal thereto which is in some cases very desirable. Inaddition, this procedure provides means for readily ascertaining anydistortion which may have taken place by observing any marks in theouter surface of the article. Moreover, by applying the hard chromium lm28 as a last step in the process, any irregularities or distortionpresent in theV metallic structure 23 can .be compensated for either bychanging'the contour of the face 25 of vthel malleable layeror'foundation shell 28 or ing a visual indication which readily apprisesVthe I operator of any Wearing'of the working surface of the die. Thisindication is very noticeable when the working surface of the die is ofchromium and the underlying metal employed is copper, as the lattergives a yellowish cast to the area subject to undue wear before thesurface 25 of the copper shell is impaired. The foregoingfeature is verydesirable because it informs vthe operator that the die is due forreconditioning before appreciable changes in dimensions and contour havetaken place which in many cases destroy the dies usefulness causing itsimmediate lobsolescence as in present practice undue Wear of thevworking areas prevents the possible reconditioning of a die. ing metalwhich, as hereinbefore pointed out, is capable of withstanding theapplication of physical or chemicalagents for the removal of thechromium facing without impairment allows that the die could' bere-established to its original di-' mensions and used again by onlyapplying a chromium coating having a predetermined thickness.

The reconditioning of the die when wear of its face metal has takenplace can be accomplished Y very effectively by stripping or removingthe hard face metal or chromium lm 28 by any suitable means such as bythe application of hydrochloric or muriatic acid which Will remove thechromium.' Afrom the foundation metal or copper shell 2D so that thesurface 25 will be clear of any chromium layer. After the surface 25 ofthe foundation metal 20 is free from impurities the same Moreover, theunderlyis established as a cathode for the electro-depo-f.:

sition thereon of a new hard chromium film or face layer'. The chromiumlm should have the same thickness as the layer 28 originally applied tothe copper shell 28. i

i 1 contemplate within the spint `of the inve'n-g,

Y tion to produce a die, mold or forming tool which will comprise thehard face metal or ne chromium lm 28 bonded tothe primary base v22 orvto a reinforcing or supporting base structure 32.

This type of die can be accomplished by follow-,

ing the steps contemplated to produce the foundation shell 20 and itsreinforcing backings prior to the application of the face metal 28, bydissolving or removing the copper shell 20 by the application of nitricacid thereto and thereafter,-

electro-depositing upon the primary base or chromium backing 22 the hardface metal layer 28 building up the chromium deposition to a thicknesscorresponding to the coatings applied to treat the article andestablishing selected surface as a cathode as Well as the thickness ofthe foundation metal 20 so that the die will have the exact form andaccurate dimensions of the model.

It is also contemplated within the spirit of the invention that in caseswherein the model or contour to be duplicated is made of a base typemetal such as copper, nickel or cobalt, the foundation metal or coppershell 20 and the steps contemplated to produce the same can be dispensedwith and a die can be produced by electro-depositing on the selectedmetallic surface of the model a chromium film of ne quality which willform the face 28 or the wearing surface of the die and thereafterapplying suitable reinforcing or supporting bases such as 22 and 32. Icontemplate the removal of the article from the chromium face 28 of thedie proper by dissolving the article through the use of a suitablechemical agent such as by applying a nitric acid thereto so that theforming tool or die will comprise a chromium layer or lm 28 of finequality constituting the working surface of the die and suitablereinforcing bases or supporting structures bonded thereto.

In the practical application of the invention the method has beendescribed with reference to the production of the lower section I4 ofthe die block, but it is contemplated thatl the upper element I2 can beproduced by following the steps hereinbefore enumerated. In such case,the upper surface of the paper weight I5 is arranged in lieu of the baseI6 to receive the metallic depositions to produce a composite metallicstructure having the shape and configuration of the die element I2 ofthe die block.

It is apparent that, withinthe scope of the invention, modifications @ddifferent arrangements may be made other than is herein disclosed, andthe present disclosure is illustrative merely, the inventioncomprehending all variations thereof.

What I claim is:

1. A die including a foundation metal having a die surface face a layerof chromium of substantially uniform thickness covering the face of saidfoundation metal; the foundation metal having a different color anddegree of hardness than that of said layer, and its face formed to theshape of the working surface of the die; and a chromium backingdeposited on the back of said foundation metal.

2. A die including a layer of chromium of substantially uniformthickness constituting the working surface of the die and being bondedto a cobalt supporting shell; the supporting shell formed t0 the shapeof the working surface of the die made by electrolytic deposit; and achrorrliun backing bonded on the rear surface of said s e 3. A dieformed of superimposed metals including a layer of chromium ofsubstantially uniform thickness constituting the working surface of thedie; a metallic foundation of nickel bonded to said chromium layer theface of the metallic foundation formed to the shape of the workingsurface of the die; a layer of chromium bonded to the rear surface ofsaid metallic foundation forming a covering therefor; and a metallicbacking bonded to said chromium covering.

CARL J. WELCOME.

